Lilach Gavish

Irradiation with 780 nm diode laser attenuates inflammatory cytokines but upregulates nitric oxide in lipopolysaccharide-stimulated macrophages: implications for the prevention of aneurysm progression.

Low level laser irradiation (LLLI) has been shown to reduce inflammation in a variety of clinical situations. We have shown that LLLI (780 nm) increases aortic smooth muscle cell proliferation and matrix protein secretion and modulates activity and expression of matrix metalloproteinases. Inflammation is a major component of arteriosclerotic diseases including aneurysm. Macrophage recruitment and secretion of pro‐inflammatory cytokines and the vasodilator, nitric oxide (NO), are central to most immune responses in the arterial wall. The present study was designed to determine the effect of LLLI on cytokine gene expression and secretion as well as gene expression of inducible nitric oxide synthase (iNOS) and NO production in lipopolysaccharide (LPS)‐stimulated macrophages.

Low-level laser irradiation inhibits abdominal aortic aneurysm progression in apolipoprotein E-deficient mice

AIMS Increased early detection of abdominal aortic aneurysm (AAA) and the severe complications of its current treatment have emphasized the need for alternative therapeutic strategies that target pathogenetic mechanisms of progression and rupture. Recent in vitro studies from our laboratory have shown that low-level laser irradiation (LLLI) (780 nm) modifies cellular processes fundamental to aneurysm progression. The present study was designed to determine whether LLLI retards the progression of suprarenal AAA in vivo. METHODS AND RESULTS High-frequency ultrasonography (0.01 mm resolution) was used to quantify the effect of LLLI on aneurysmatic aortic dilatation from baseline to 4 weeks after subcutaneous infusion of angiotensin II by osmotic minipumps in the apolipoprotein E-deficient mouse. At 4 weeks, seven of 15 non-irradiated, but none of the 13 LLLI, mice had aneurysmal dilatation in the suprarenal aneurysm-prone segments that had progressed to >or=50% increase in maximal cross-sectional diameter (CSD) over baseline (P = 0.005 by Fishers exact test). The mean CSD of the suprarenal segments (normalized individually to inter-renal control segments) was also significantly lower in irradiated animals (LLLI vs. non-irradiated: 1.32 +/- 0.14 vs. 1.82 +/- 0.39, P = 0.0002 by unpaired, two-tailed t-test) with a 94% reduction in CSD at 4 weeks compared with baseline. M-mode ultrasound data showed that reduced radial wall velocity seen in non-treated was significantly attenuated in the LLLI mice, suggesting a substantial effect on arterial wall elasticity. CONCLUSION These in vivo studies, together with previous in vitro studies from this laboratory, appear to provide strong evidence in support of a role for LLLI in the attenuation of aneurysm progression. Further studies in large animals would appear to be the next step towards testing the applicability of this technology to the human interventional setting.

Low level laser arrests abdominal aortic aneurysm by collagen matrix reinforcement in apolipoprotein E‐deficient mice

Recent in vitro studies by our group indicated that low level laser irradiation (LLLI) modifies cellular processes essential to the progression of abdominal aortic aneurysm (AAA). Using high‐frequency ultrasonography (HF‐u/s) in the angiotensin‐II (Ang‐II)‐infused, apolipoprotein‐E‐deficient (Apo‐E−/−) mouse model of AAA, we found that LLLI markedly inhibited aneurysm formation and preserved arterial wall elasticity. We now report, using quantitative histopathology, the likely mechanism underlying the preventative effect of LLLI on aneurysm formation in this model.

Inadequate reinforcement of transmedial disruptions at branch points subtends aortic aneurysm formation in apolipoprotein-E-deficient mice

INTRODUCTION Infusion of angiotensin-II (Ang-II) in apolipoprotein-E-deficient mice (Apo-E(-/-)) results in suprarenal abdominal aortic aneurysm (AAA) in 30-85% of cases. This study identifies the apparent mechanism by which some animals do, but others do not, develop AAA in this model. METHODS Male Apo-E(-/-) mice were infused with Ang-II (n=21) or saline (n=6) and sacrificed at 4 weeks. Aortas were excised, embedded in paraffin, sectioned (250 μm intervals), and stained. Sites of transmedial disruption (TMD) were identified and characterized, and their relationship to the 4 major aortic side branches (celiac, superior mesenteric, and renals) were determined. RESULTS The frequency of TMDs in Ang-II-infused mice that formed AAA (n=9) was similar to those that did not (n=12) (AAA vs. no-AAA: 25 of 36[69%] vs. 28 of 48[58%] branches, P=.3 by chi-square). All TMDs were at branch points. However, in animals with AAA, the mean maximum length of the TMDs was significantly larger (1.94±1.6 vs. 0.65±0.5mm, P=.007 by Mann Whitney U test), the #mac-2(+) macrophages per 0.01mm(2) of defect area was greater (32±10 vs. 19±11, P<.02 by Kruskal-Wallis with Conover-Inman post hoc), the % area of attempted repair occupied by collagen was less (17±13% vs. 44±15%, P=.0009 by Mann Whitney U test), and the density of collagen per unit length of media missing was also markedly less (0.13±0.2 vs. 1.14±1.0, P=.0001 by Mann Whitney U test). CONCLUSIONS Reinforcement of transmedial defects at branch points by wall matrix is a key intrinsic player in limiting AAA formation in the Ang-II-infused, Apo E(-/-) mouse and a potentially important mechanism-based therapeutic target for management of small, slowly progressing aneurysms.

Arrest of progression of pre‐induced abdominal aortic aneurysm in apolipoprotein E‐deficient mice by low level laser phototherapy

Using non‐invasive, high‐frequency ultrasonography (HF‐u/s), we showed that low‐level laser phototherapy (LLL) inhibits de‐novo formation of abdominal aortic aneurysms (AAA) in apolipoprotein‐E‐deficient (Apo‐E‐/‐) mice. The current study tests the effect of LLL on the progression of pre‐induced AAA.

Contradictory effects of hypercholesterolemia and diabetes mellitus on the progression of abdominal aortic aneurysm.

Hypercholesterolemia and type 2 diabetes mellitus (DM) are well-established risk factors for atherosclerotic occlusive disease. However, of the 2, only the former is a risk factor for abdominal aortic aneurysm (AAA). In this editorial, we point out the principal epidemiologic and pathobiologic differences between the effects of hypercholesterolemia and DM on AAA growth, lessons learned related to these mechanisms from nonhuman studies including preventative effects of experimental phototherapy by low-level laser, and implications for novel mechanismebased treatment approaches.

Lessons from Animal Models of Arterial Aneurysm.

We review the results from the most common animal models of arterial aneurysm, including recent findings from our novel, laparoscopy-based pig model of abdominal aortic aneurysm, that contribute important insights into early pathogenesis. We emphasize the relevance of these findings for evaluation of treatment protocols and novel device prototypes for mechanism-based prevention of progression and rupture.

Quantification of roughness of calcific deposits in computed tomography scans of human coronary arteries

Objectives:The incidence of coronary artery disease has been shown to be greater in patients with calcific deposits than in those without. It has been suggested that the pattern of distribution of coronary calcific deposits within coronary arteries is of greater predictive value for acute coronary events than the overall quantity. Whether roughness of calcific deposits is a predictor of acute coronary events is not known. We derived and tested an algorithm, Voxel-Based Bosselation (VBB), for noninvasive quantification of roughness of calcific deposits in human coronary arteries imaged by computed tomography (CT). Methods and Results:VBB was tested on 213 coronary calcific deposits from electron beam CT scans of 27 patients. This algorithm evaluates the 3-dimensional connectedness of surface voxels of each deposit: smooth masses have low VBB and rough masses high VBB. The algorithm was calibrated with artificially generated phantoms as well as background noise mimicking calcific deposits and surrounding heart tissue. The VBB algorithm is applicable to calcific deposits of all scales and gradations. The VBB values of the deposits in this study did not correlate with deposit size further supporting its validity as a measurement of roughness. The VBB index corresponded directly with visual reconstruction using Phong-shaded algorithms. Conclusions:The VBB index, derived here, is a noninvasive method of quantifying the roughness of calcific deposits in CT scan data which can now be used in future clinical studies to determine possible correlations with increased plaque vulnerability and major acute coronary events.

Irradiation with 780 nm Diode Laser Attenuates Inflammatory Cytokines While Upregulating Nitric Oxide in LPS-Stimulated Macrophages: Implications for the Prevention of Aneurysm Progression

Low level laser irradiation (LLLI) has been shown to reduce inflammation of tissue and we show that 780 nm radiation modifies certain processes fundamental to aneurysm progression. This study has been designed to determine the effect of LLLI on cytokine gene expression and secretion of inductible nitric oxide synthase (iNOS) and NO production in lipopolysaccharide (LPS) - stimulated macrophages.